The present invention relates to an improvement in straight rod stock processors of that type employed for the shearing and bending of concrete reinforcing bar, and in particular is the electro-mechanical combination of a rod stock loader with a stirrup bender, being distinguished, however, by the incorporation of a set of secondary rod stock compression rollers positioned just forward of the stirrup bender shear blade in order to pick-up and infeed that three-to-five foot length of rod stock remaining between the loader feed compression drive wheels and the stirrup bender shear blade, so that essentially the entire length of a piece of straight rod stock is delivered to the bender head for making product thus minimizing waste and handling, and making the processing economies of using lower cost per ton straight rod stock for producing concrete reinforcing shapes competitive with that of the coil-fed stirrup benders.
Exemplary of the coil-fed stirrup benders is that as taught by Ritter et al in U.S. Pat. No. 5,193,378 dated Mar. 16, 1993, wherein reinforcing bar material is infed from a coil (not shown) by a set of compression feed rollers 4 through measuring rollers 11 to a series of straightening rollers 5 to remove the coil bend and furnish a straight rod length segment for delivery to the shear station 8 and bender head 9 whereby bending of product (stirrups) B is accomplished. The distance between the straightening rollers 5 and the shear station 8 in such machines is typically three-to-five feet, which is the length of the waste tail at the end of processing a thousand-foot or so coil of reinforcing bar material, and in terms of total length of the coil processed is not a substantial amount of waste. Therefore, although the cost per ton of coil material is higher, the handling efficiencies and relatively low waste make such an alternative competitive with the lower cost per ton straight rod stock. Thus, when one is infeeding forty to sixty-foot lengths of straight rod stock through such a machine, and there is a three-to-five foot piece of waste for each piece of straight rod stock thus fed for processing, the cumulative waste amount quickly becomes substantial and with the increased handling requirements involved with piece-feeding affects even more substantially the otherwise lower material cost advantage of using straight rod stock.
Another technique for infeeding coil stock to a stirrup bender is by a reciprocating gripper means as taught by DelFabro et al in Fr. Pat. No. 2,553,314 dated Apr. 19, 1985, as therein illustrated in FIG. 1. Again, however, were such a machine used for infeeding and processing pieces of straight rod stock similar production efficiency, waste consideration, and material cost differential factor results would obtain as heretofore described.
The applicant herein, by his invention provides a machine combination and method which overcomes those above-identified offsetting factors which otherwise mitigate against competitive use of straight rod stock as opposed to coil stock in the stirrup bending of concrete reinforcing bar shapes.